There’s a lot about fertility we are yet to discover. Scientists are discovering more every single day about what it takes for a sperm cell to fertilize an egg. This year, UCSF scientists uncovered hoe progesterone switches on a sperm’s internal electricity which is involved in giving the sperm enough power to push toward the egg. This discovery could lead to understanding more about fertilization. Fertilization problems are difficult to diagnose.
Two recent articles in the scientific journal Nature — one by Lishko and Kirichok, another by researchers in Germany — provide the first evidence that progesterone activates sperm tails by binding to a protein on the sperm’s surface, called CatSper. Scientists have long suspected that progesterone from around the egg triggers sperm tails to pump harder in the final stages of fertilization. The tail’s normal undulations switch to a one-sided flicking motion, like a whip being cracked against the ground.
Called “hyperactivation,” the whipping motion is thought to give sperm a last-minute boost to the egg and help one lucky winner poke through the egg’s protective vestments. In fact, in vitro experiments show that fertilization cannot happen without hyperactivation. But until now, researchers couldn’t explain how progesterone transmits its signal.
Contact with CatSper starts a rush of electrically charged calcium ions into the cell, the new research found. While the sperm tail contains no real muscle, it is constructed of some of the same molecules. So just as muscles contract in response to calcium currents, the sperm tail reacts with a forceful twitch.
In the future, doctors may be able to screen the genes of infertile men for defects in CatSper and other sperm proteins. These crucial molecules have been tough to identify so far. But the advent of electrical recordings in human sperm could change how we evaluate infertile couples.
Watch hyperactivated sperm here: http://bcove.me/h9f0y0n9